Method of preparing mixed electrolyte powder for bicarbonate dialysis and powder mixture formed
Patent 4655941 Issued on April 7, 1987. Estimated Expiration Date: 
October 1, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
October 1, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3112239 3196930 3560380 3882020 Hemo dialyzer employing two dialysate solutions Apparatus and method for preparation of a hemodialysis solution optionally containing bicarbonate Stable supersaturated solutions of sparingly soluble salts Aqueous acid concentrate for hemodialysis dialysate Materials and method for preparing dialysis solutions containing bicarbonate ions Patent #: 4489535 InventorAssigneeApplicationNo. 06/789965 filed on 10/01/1985US Classes:252/1, MISCELLANEOUS (E.G., ARTIFICIAL SNOW)159/48.1, Spraying210/321.71, Dialyzer with dialysate proportioning means210/647, Maintaining critical concentration(s)210/96.2, With membrane23/303, Common salt252/189, CO, S, NEGATIVE ELEMENT, OR ACID, BINDANT CONTAINING252/190, With absorbents252/193, AMMONIA, ALKALI OR BASE, BINDANT CONTAINING422/902SODIUM CHLORIDE AND POTASSIUM CHLORIDE DISSOLVERExaminersPrimary: Terapane, John F.Assistant: Thexton, Matthew A. Attorney, Agent or FirmInternational ClassesA61K 33/14 (20060101)A61K 9/14 (20060101) A61M 1/16 (20060101) DescriptionTECHNICAL FIELDThis invention relates to a method of preparing a mixed electrolyte powder for bicarbonate dialysis (dialysis using a bicarbonate-containing dialyzing fluid) and, more particulary, to a method of preparing a novel mixed electrolyte powder withwhich a specific electrolyte ion composition and an appropriate pH can be secured always in a constant manner through mere dissolution thereof in water and thereby an electrolyte solution for perfusing artificial kidney systems for bicarbonate dialysiscan be prepared. BACKGROUND ART The bicarbonate-containing artificial perfusing fluid is one of the dialyzing fluids for perfusing artificial kidney systems and generally comprises a concentrated aqueous solution of various electrolytes necessary for hemodialysis (compositionA) and a concentrated aqueous solution of sodium bicarbonate powder alone or in combination of part of the above-mentioned electrolytes (e.g. NaCl, CH3 COONa) (composition B). These compositions are placed in the respective tanks of an artificialkidney system for bicarbonate dialysis and, at the time of use, they are diluted with water and mixed together to give a dialyzing fluid. Such dialyzing fluid, which contains sodium bicarbonate (as composition B) originally known to be a factor directlyadjusting the body fluid pH and hence physiologically adequate, efficiently and rapidly improves the acid-base balance in metabolic acidosis, respiratory alkalosis and the like, does not provoke indefinite complaints, such as hypotension and nausea,during dialysis, and can accomplish rapid dehydration. Therefore, said fluid is much expected to be effective and safe in the treatment of hyperpotassemia, hypocalcemia, hyperphosphoremia and hyperaceta, for instance, and especially in large-areashort-time dialysis. However, the above-mentioned sodium bicarbonate is low in solubility and unstable against acid pH and heat. Accordingly, it has the fatal disadvantage that, in preparing dialyzing fluids by admixing it with composition A and during storage ofsaid fluids, it generates carbon dioxide gas and thereby causes increase of pH and decrease of carbon dioxide gas pressure, whereby calcium and magnesium in composition A precipitate out in the form of carbonate. Therefore, in preparing theabove-mentioned bicarbonate-containing dialyzing fluids, the prior art used the technique of introducing carbon dioxide gas into the mixing tank (reaction vessel) to thereby compensate the loss of carbon dioxide gas due to escape and thus maintain the pHof the dialyzing fluids at or around the neutral pH or the technique of adding an appropriate amount of a mineral acid or organic acid to the above reaction vessel or composition A to thereby adjust the pH. However, these procedures themselves arerather complicated or troublesome and, in addition, highly precise concentration and pH control is required. Moreover, the above composition A itself is a concentrated solution, so that its storage stability cannot be secured, namely pH changes with thelapse of time, for example during storage, are unavoidable. The large volume and weight of such solution are its further disadvantages in its handling, such as transportation. It is an object of the present invention to provide a method of producing a uniform-quality powder-form composition A for preparing bicarbonate-containing dialyzing fluids, which can be produced in an easy manner and on a commercial scale and inwhich necessary electrolyte ions are in a very uniformly mixed state without substantial variation in composition, and thereby solve not only the problems hitherto encountered in preparing bicarbonate-containing dialyzing fluids but also the stabilityand handling problems. DISCLOSURE OF THE INVENTION The present invention provides a method of producing a mixed electrolyte powder having an electrolyte ion composition suited for use in preparing a dialyzing fluid for perfusing artificial kidney systems for bicarbonate dialysis, which methodcomprises a step of pulverizing the whole or part of sodium chloride, which is one of the components of the above powder, in a micronizer to a microfine powder having a particle size of about 20-30 μm and adding thereto 2-4 percent by weight ofglacial acetic acid by spraying, whereby a microfine powder of sodium chloride acidified with acetic acid is obtained, a step of dissolving other components constituting the above mixed powder and, if any, the remaining portion of sodium chloride in warmwater and spray-drying the solution using a spray nozzle or disk atomizer to a microfine powder having a particle size of about 20-100 μm, and a step of mixing both the microfine powders obtained in the above steps together. In accordance with the invention, a mixed electrolyte powder very useful as composition A for bicarbonate dialysis can be produced. A desired pH value can be obtained by mere dissolution of said powder in water. An advantageous feature of the invention consists in that the powder product obtained by using the above-mentioned microfine powder of sodium chloride acidified with acetic acid, when dissolved in water for use as composition A, gives an adequatepH and therefore will not cause any abnormal carbon dioxide gas generation, any decrease in carbon dioxide pressure, any local pH increase or the like or will not incur any substantial risk of causing precipitation of calcium or magnesium in the form ofcarbonate. Another advantageous feature of the invention lies in that, irrespective of specific gravity differences, the necessary electrolyte components of the above-mentioned composition A, including in particular KCl which is a trace component, can bemade up into a homogeneous microfine powder uniform in particle size by spray-drying an aqueous solution of said components. The microfine powder consists of minute spherical particles each having a constant specified composition, is nonhygroscopic andstable and, furthermore, is close in particle size to acetic acid-acidified sodium chloride to be mixed therewith, so that these can be mixed together very easily. A third advantageous feature of the invention is that, owing to the above second advantage, such powder product which is composed of particles constant in electrolyte composition and uniform in size can be produced in a large quantity at a timeby a simple and easy mixing procedure. Whereas it is in general difficult to mix two or more components differing in particle size to a homogeneous powder and such mixing becomes still more difficult especially when the components are to be mixed inwidely different proportions and on a large scale, no such difficulties are encountered with the method of the present invention. The powder product obtained in accordance with the invention, when distributed in packagings, does not reveal anysubstantial variation in electrolyte composition among batches. It is a further advantage of the method of the invention that, since it occurs as a powder, the product, when packed in a hermetically sealed condition, can be stored, transported and otherwise handled in a simple and easy manner and can stablyretain its constant quality during a prolonged period of time, without substantial changes in quality, such as changes in pH. When the mixed powder obtained by the method of the invention is used, it is possible to prepare, very easily, bicarbonate-containing dialyzing fluids always constant and adequate in pH, electrolyte composition, carbonate ion concentration,carbon dioxide gas pressure and other respects. The bicarbonate-containing dilyzing fluids thus prepared of course produce their particular, excellent effects in hemodialysis, such as improvement of metabolic acidosis or reduction in the frequency ofindefinite complaints, and the above effects become more remarkable especially because the dialyzing fluid preparation is easy and there occurs no great variation in quality. In the method of the present invention, it is essential to use an acetic acid-acidified sodium chloride powder treated in a special manner. As the sodium chloride material to be used in carrying out said method, there is used that sort of sodiumchloride which is listed in the Japanese Pharmacopeia, occurs as crystals or a crystalline powder, contains not less than 99.5% of NaCl and generally has a particle size of about 500-600 μm. In accordance with the invention, such sodium chloride ispulverized to a particle size of about 20-30 μm using a micronizer. Although the kind of micronizer is not critical, that type with which pulverization and classification can be realized simultaneously and a fraction having the desired particle sizecan be separated out is preferred. The rotor speed can be suitably within the range of 7,000-8,000 rpm (revolutions per minute) and the separator speed within the range of 2,000-3,000 rpm. The particle size of the sodium chloride prepared in the abovemanner should be within the range of about 20-30 μm. Such sodium chloride powder can retain its favorable powder condition even after the subsequent addition of glacial acetic acid by spraying. In accordance with the invention, glacial acetic acid is added to the above microfine sodium chloride powder by spraying. The spraying is performed in an appropriate vessel such as a rotary stirrer vessel. As the glacial acetic acid, there isused glacial acetic acid containing not less than 99.0% of CH3 COOH (60.05) and meeting the requirements of Japanese Pharmacopeia or JIS (Japanese Industrial Standard) for special reagent grade glacial acetic acid. More detailedly, the spraying canbe conducted using a pressure nozzle set in the central part of a rotary stirrer vessel, for instance. The amount of glacial acetic acid to be added by spraying is within the range of 2-4 percent by weight based on the sodium chloride weight. Theacetic acid-acidified sodium chloride obtained by the addition of glacial acetic acid in said amount can hold its powder condition, and the mixed electrolyte powder of the invention obtained by using such sodium chloride, when dissolved in water inpreparing composition A for the preparation of bicarbonate-containing dialyzing fluids, allows said composition A to have an ideal pH value, namely a pH of about 4.5. The good flowability of the acetic acid-acidified sodium chloride powder thus obtainedis presumably due to the phenomenon that a huge number of very minute sodium chloride particles are adsorbed on each of glacial acetic acid droplets sprayed in the manner of mist, resulting in the above powder each particle of which is composed of suchgroup of microfine sodium chloride particles and said acetic acid droplet surrounded by said particles. Anyhow, the powder obtained remains stable and retains its flowability for a long period of time and can be admixed with other powders without anydrying in advance. As the other electrolytes to be mixed in powder form with the acetic acid-acidified sodium chloride powder obtained in the above process, there may be used compounds conventionally used as the material for preparing dialyzing fluids, morespecifically potassium chloride (KCl), calcium chloride (CaCl2.2H.sub.2 O), magnesium chloride (MgCl2.6H.sub.2 O) and sodium acetate (CH3 COONa or CH3 COONa.3H2 O), each listed on the Japanese Pharmacopeia, Japanese FoodAdditives Standards, or JIS (for reagents). These electrolytes are dissolved in warm water and the solution is spray-dried to a microfine powder about 20-100 μm in particle size using a spray nozzle or disk atomizer. The above warm water preferablyhas a temperature of about 35°-40° C. The dissolution is generally carried out with stirring. The aqueous solution obtained is preferably an aqueous solution concentrated as much as possible. A concentration of about 35% is generally asappropriate one. The spray drying of the above warm aqueous solution is performed using a spray nozzle or disk atomizer. The spray drying conditions are selected such that a microfine powder having a particle size of about 20-100 μm can be obtained. As thespray nozzle, there is preferably used a nozzle having an orifice diameter of about 1.0-2.0 mm. The disk atomizer is rotated preferably at a speed of about 10,000-30,000 rpm. The spray drying temperature conditions are such that the temperature at theinlet to the drying chamber is generally about 200°-400° C., preferably about 350°-400° C., and the outlet temperature is generally about 100°-200° C., preferably about 150°-200° C. Theliquid-sending pump pressure in spray drying may be selected in an optional manner with 10 kg/cm2 as the general standard. The drying time required is generally very short and the desired mixed powder can be obtained in several seconds to severaltens of seconds. The mixing ratio among the electrolytes to be spray-dried in the above process is selected such that bicarbonate-containing dialyzing fluids prepared by dissolving in water the spray-dried powder thus obtained and the previously mentioned, aceticacid-acidified sodium chloride powder, followed by mixing the solution with composition B (NaHCO3 solution) have the following ion composition: ______________________________________ Na.sup. 135-140 mEq/l K.sup. 0-4.0 mEq/l Ca2 2.5-3.5 mEq/l Mg2 1.0-1.5 mEq/l Cl- 106-107.5 mEq/l CH3 COO- 7-9 mEq/l HCO3- 27.5-35 mEq/l ______________________________________ The above CH3 COO- concentration is the total of the concentration of CH3 COONa or CH3 COONa.3H2 O (4-6 mEq/l as CH3 COO-) from the spray-dried powder and that of CH3 COOH constituting the aceticacid-acidified sodium chloride powder. The dialyzing fluids having the above ion composition preferably contain the electrolytes and NaHCO3 in the following weight proportions: ______________________________________ NaCl 59.474-62.644% by weight KCl 1.157-1.998% by weight CaCl2.2H.sub.2 O 0.978-2.738% by weight MgCl2.6H.sub.2 O 0.676-1.634% by weight CH3 COONa 1.455-6.595% by weight NaHCO324.763-30.562% by weight ______________________________________ The NaCl as one component of the above composition may wholly be in the acetic acid-acidified powder form. In that case, the mixed powder according to the invention (exclusive of composition B) preferably has the following composition: ______________________________________ CH3 COOH--acidified NaCl 83.263-88.887% by weight KCl 0-4.415% by weight CaCl2.2H.sub.2 O 2.720-3.875% by weight MgCl2.2H.sub.2 O 1.505-2.296% by weight CH3 COONa 4.048-8.767% byweight ______________________________________ Alternatively, the above NaCl to be used in preparing the above composition may partly be in the acetic acid-acidified powder form, with the remaining portion being in the spray dried powder form. In this case, it is recommendable that theportion of NaCl converted to the acetic acid-acidified powder form should amount to 40-60 percent by weight, preferably about 50 percent by weight, based on the whole amount of the mixed powder according to the invention (composition A). This possiblyfacilitates the homogeneous mixing of said powder with the spray-dried powder. When packed in a hermetically sealed condition, the mixture obtained in accordance with the invention can become a very easy-to-handle product retaining good preservability for a long period of time. Said product can be used directly ascomposition A for preparing bicarbonate-containing dialzying fluids, the only requirement being to dissolve the same in an appropriate amount of water. The thus-obtained composition A can be expected to produce satisfactory effects without adding anadditional portion of acid at the time of mixing with composition B or blowing carbon dioxide gas into the mixing vessel. In other words, the powder obtained in accordance with the invention, when dissolve in water in preparing dialyzing fluids, gives asolution (composition A) having an ideal pH value of about 4.5 and, on the other hand, composition B (aqueous solution) has a pH of about 8. Therefore, the resultant dialyzing fluids can have a pH of about 7.3 which is adequate for hemodialysis. TheHCO3- concentration in said dialyzing fluids is such that the pCO2 value is maintained at a constant level of about 60 mmHg, which is adquate for the dialyzing fluids, as a result of the reaction between CH3 COOH in composition A andNaHCO3 in composition B as shown in the following: The following examples illustrate the invention in further detail. EXAMPLE 1 Potassium chloride (KCl) meeting the requirements of Japanese Pharmacopeia (26.24 kg), calcium chloride (CaCl2.2H.sub.2 O) meeting the requirements of Japanese Pharmacopeia (36.22 kg), magnesium chloride (MgCl2.6H.sub.2 O) of foodadditive grade (21.46 kg) and anhydrous sodium acetate (CH3 COONa) of food additive grade (40.48 kg) were dissolved in deionized water to make the whole volume 420 liters. With warming and stirring, the solution was led to a spray drier, where thesolution was dried at an inlet temperature of 300° C.-350° C. while rotating a disk atomizer at a speed of 18,000 rpm. There was thus obtained a uniform, microfine powder (20-30 μm in particle size) containing the ions of theabove-mentioned electrolytes. Separately, Sodium chloride (NaCl) of Japanese Pharmacopeia grade (875.6 kg) was pulverized in a microanalyzer (8,000 rpm) until a microfine powder (about 20-30 μm in particle size) was obtained. This powder was stirred in a stirrer andthereto was added glacial acetic acid of Japanese Pharmacopeia grade (26.4 kg) by spraying. Thus was obtained a microfine sodium chloride powder acidified with acetic acid. The previously mentioned microfine powder from the spray drier was introduced into the acetic acid-acidified, microfine sodium chloride powder, followed by stirring until homogeneity was attained. There was obtained a powder of the invention. This powder product was used as composition A. Thus, it was hermetically packed in 2,486-g portions. Separately, sodium hydrogen carbonate (NaHCO3) meeting the requirements of Japanese Pharmacopeia, as composition B, was hermetically packedin 882-g portions. EXAMPLE 2 Sodium chloride (NaCl) of Japanese Pharmacopeia grade (375.6 kg), potassium chloride (KCl) of Japanese Pharmacopeia grade (26.24 kg), calcium chloride (CaCl2.2H.sub.2 0) of Japanese Pharmacopeia grade (36.22 kg), magnesium chloride(MgCl2.6H.sub.2 O) of food additive grade (21.46 kg) and anhydrous sodium acetate (CH3 COONa) of food additive grade (40.48 kg) were dissolved in deionized water to make the whole volume 1,500 liters. With warming and stirring, the solutionwas led to a spray drier, where it was dried by spraying under pressure form a spray nozzle having an orifice diameter of 1.2 mm at an inlet temperature of 300°-350° C. A homegeneous, microfine powder (50-100 μm in particle size)containing the ions of the above-mentioned electrolytes was obtained. Separately, sodium chloride (NaCl) of Japanese Pharmacopeia grade (500 kg) was pulverized in a microanalyzer (8,000 rpm) to a microfine powder (about 20-30 μm). To this powder, there was added, with stirring in a stirrer, glacial acetic acid(CH3 COOH) of Japanese Pharmacopeia grade (26.4 kg) by spraying to give an acetic acid-acidified, microfine powder of sodium chloride. Equal amounts of the above two microfine powders were mixed together until homogeneity was attained, to give a powder product according to the invention. The powder product obtained, as composition A, was hermetically packed in 2,486-g portions. Separately, sodium hydrogen carbonate (NaHCO3) of Japanese Pharmacopeia grade, as composition B, was hermetically packed in 882-g portions. One pack of the composition A obtained either in Example 1 or in Example 2 was dissolved in water to make 10 liters to give solution A (pH about 4.5). One pack of the composition B (NaHCO3 in each case) was dissolved in water to make 20liters to give solution B (pH about 8.1). Both the solutions were charged into the main solution tank (for solution A) and aqueous bicarbonate tank (for solution B) of a bicarbonate-containing dialyzing fluid supplying apparatus (Nypro (Japan) modelKH-20 AB). From the supplying tacks, they were fed to a mixing tank, where they were mixed and diluted with warm water (35°-40° C.) such that the total volume was made 350 liters. The mixed dilution was further sent to the terminalconsole, where the bicarbonate-containing dialyzing fluid was measured for respective electrolyte ion concentration, pH PCO2 and pO2. The results thus obtained are summarized below in Table 1 and Table 2. The Na.sup. and K.sup. ions weredetermined by using a flame photometer (Instrumentation Laboratories (USA) model 343), the HCO3- ion concentration, pCO2 and pO2 by using a gas analyzer (Instrumentation Laboratories model Micro 13 meter) and the Ca2 , Mg2 ,CH3 COO- and Cl- ion concentrations by the methods respectively prescribed in the Japanese Pharmacopeia and Japanese Food Additives Standards. TABLE 1 __________________________________________________________________________ Theoretical value Na.sup. K.sup. Ca2 Mg2 Cl- CH3 COO- HCO3- __________________________________________________________________________ Measured value 135 2.5 3.5 1.5 106.5 8-9 27-28 Example No. 1 134.6 2.4 3.4 1.4 106.7 8.3 28.0 1 No. 2 135.2 2.5 3.5 1.5 107.4 8.4 27.2 No. 3 134.7 2.4 3.5 1.5106.4 7.9 27.8 No. 4 135.3 2.5 3.4 1.4 107.3 8.3 27.3 No. 5 134.7 2.4 3.4 1.5 106.8 8.0 27.7 Mean (-x) 134.90 2.44 3.44 1.46 106.92 8.18 27.60 Example No. 1' 135.2 2.5 3.5 1.5 106.8 8.4 27.5 2 No. 2' 135.0 2.5 3.5 1.5 106.4 8.0 27.9 No. 3' 135.1 2.5 3.4 1.5 106.7 8.3 27.3 No. 4' 134.9 2.4 3.5 1.4 106.3 8.1 27.4 No. 5' 134.9 2.5 3.4 1.5 106.4 8.3 27.8 Mean (-x) 135.02 2.48 3.46 1.48 106.52 8.22 27.58 (mEq/l) __________________________________________________________________________ TABLE 2 ______________________________________ HCO3- Lot No. pH Pco2 (mmHg) Po2 (mmHg) (mEq/l) ______________________________________ Example No. 1 7.24 63.3 115.5 28.0 1 No. 2 7.30 60.7 116.0 27.2 No. 3 7.22 61.8123.1 27.8 No. 4 7.26 59.4 119.4 27.3 No. 5 7.27 61.0 120.2 27.7 Mean (-x) 7.26 61.24 118.84 27.60 Example No. 1' 7.25 62.7 122.7 27.5 2 No. 2' 7.25 63.0 119.8 27.9 No. 3' 7.23 61.8 118.2 27.3 No. 4' 7.25 61.2 120.6 27.4 No. 5' 7.26 62.2 121.227.8 Mean (-x) 7.25 62.18 120.50 27.58 ______________________________________ The above results indicate that, even in large-batch-size commercial production, the method of the invention can attain satisfactory mixture homegeneity with respect to the electrolyte ions and further that the solution prepared by meredissolution in water holds a pH value suited for hemodialysis using a bicarbonate-containing dialyzing fluid, with good reproducibility, and holds a pCO2 value of about 60 mmHg (pCO2 being a factor for maintaining the HCO3- ionconcentration at a level near the theoretical value). The products of Example 1 and 2 were respectively packed in laminated aluminum foil bags (three-layered film; 12 μm polyethylene, 9 μm aluminum foil and 70 μm polyethylene), followed by sealing. Among the results of analysis performedimmediately after production, 3 months later, 6 months later and 12 months later, there were noted no significant differences. |
